Storage subsystems, such as magnetic tape libraries, are widely used for storing information in digital form. Tape storage subsystems typically include one or more tape drives for reading and writing data to removable tape cartridges. FIG. 1 shows a simplified view of an exemplary tape drive 100 having a removable tape cartridge 106 loaded therein. The tape cartridge 106 typically comprises a cartridge housing enclosing a tape medium 110 wound about a rotatable supply reel 108. The tape drive 100 typically includes a take-up reel 101, a plurality of rollers 102, and a read/write head 104. The take-up reel 101 includes a take-up leader that is coupled to a supply leader extending from one end of the tape medium 110, when the tape cartridge 106 is loaded into the tape drive 100. The tape medium 110 typically comprises a thin film of magnetic material which stores the data. To read or write data, the tape medium 110 is spooled between the take-up reel 101 and the supply reel 108, with rollers 102 guiding the tape medium 110 across the read/write head 104. Upon insertion of the tape cartridge 106 into the tape drive 100, the tape medium 110 on the cartridge reel 108 is coupled to the take-up reel 101 of the tape drive 100. Subsequently, prior to removing the tape cartridge 106 from the tape drive 100, the tape medium 110 is rewound onto the cartridge reel 108 and the supply leader is then uncoupled from the take-up leader.
When performing read/write operations on the tape medium 110, it is important to maintain a proper tension in the tape medium 110, in order to maintain effective contact between the read/write head 104 without causing excessive stress on the tape medium 110. As the thicknesses of tape media and the width of data tracks on tape media continue to decrease with new technological improvements, the importance of tension control increases. Tension variation within the tape path may produce spikes in the lateral tape motion (LTM) and can cause unacceptable levels of stress in the edges of the tape medium 110.